I have owned the 1Ds, 1DsM2, and have a XT that I use as a backup. When I found out that Canon was going to release a DsM3, I sold my M2 on eBay. In the interim, Nikon of course released an awesome camera, the D3. I looked long and hard at both cameras.

Build; improved ergonomics; ability to configure settings to personal needs; great viewfinder; live view; good 3" LCD - great compared to anything previous; amazing resolution at 21.1 megapixels; fast fps ability at such high resolution

cost; could use AF in live view

2. Autofocus speed and accuracy including servo tracking are significantly improved in the Mark III camera. If you shoot action, the Mark III will give you more keepers than the Mark II. 3. Speed of image processing and file writing are blazingly fast with the Mark III.

I have to tell you that I have in my hands right now what I consider is the finest camera I've ever had the pleasure to use in more than 40 years of taking photographs, the Canon EOS-1Ds Mark III.

Canon's EOS-1Ds Mark III is the most sophisticated professional camera yet to emerge from the company's stable. Replacing the EOS-1Ds Mark II, which was released towards the end of 2004, it is the fourth in the line that began in 2002 with the EOS-1Ds and includes the EOS 5D.

Twenty-one megapixels. Think about it. Once the exclusive domain of those Tiffany-priced medium format digital backs, that same kind of high-end resolution is now possible with a D-SLR, albeit an expensive one.